Dave Evans offers the following royalty-free article for you to publish online or in print. Feel free to use this article in your newsletter, website, ezine, blog, or forum. ----------- PUBLICATION GUIDELINES - You have permission to publish this article for free providing the "About the Author" box is included in its entirety. - Do not post/reprint this article in any site or publication that contains hate, violence, porn, warez, or supports illegal activity. - Do not use this article in violation of the US CAN-SPAM Act. If sent by email, this article must be delivered to opt-in subscribers only. - If you publish this article in a format that supports linking, please ensure that all URLs and email addresses are active links. - Please send a copy of the publication, or an email indicating the URL to [email protected] - Article Marketer (www.ArticleMarketer.com) has distributed this article on behalf of the author. Article Marketer does not own this article, please respect the author's copyright and publication guidelines. If you do not agree to these terms, please do not use this article. ----------- Article Title: How To Keep Your Network in Sync Author: Dave Evans Category: Networks, Information Technology, Intra-net Word Count: 748 Keywords: ntp server, time server, gps, time synchronization, time sync, network time protocol, ntp Author's Email Address: [email protected] Article Source: http://www.articlemarketer.com ------------------ ARTICLE START ------------------
PC's and computer network infrastructure components maintain time using low-cost internal real-time clock chips. These chips are cheap to manufacture but notoriously poor at maintaining accurate time. They can drift at alarming rates, sometimes minutes each day. This can be very problematic in many computer applications such as transaction processing systems where an accurate time-line is required for ordering events. However, a solution is at hand, NTP or Network Time Protocol is widely used throughout the Internet to remedy just such problems. NTP servers are devices that obtain a precise time from an external time source such as GPS or radio time references. These devices synchronize their internal real-time clocks with the external time reference and then provide an accurate time resource for computer networks. Servers, workstations and other network device can all obtain time from the time server to maintain synchronization. The Network Time Protocol is one of the oldest Internet protocols still widely used today. Dr David Mills of the University of Delaware developed the protocol over 25 years ago. He saw a need for a mechanism to synchronise the infrastructure of the Internet. NTP has since become the de-facto standard protocol for network time synchronization throughout the Internet and in most corporate intranets. The protocol defines a number of packets of information that pass between server and client. The client 'asks' the server for time and the server responds with a packet of information containing current time and other information for round-trip delay calculation to improve accuracy. NTP is organised in a hierarchical manner, at the highest level, or stratum, sits the most accurate servers. Servers lower down the hierarchy obtain time from the level above and are slightly less accurate, mainly due to network overheads. Originally developed for the Linux operating system, NTP has now been ported to a number of other operating systems including Windows, UNIX and Novell. Indeed, most modern operating systems have an integrated NTP or SNTP client. Additionally, software can be freely downloaded under a public licence from the NTP website. Configuring NTP client software is very straightforward. Minimally, the client only requires the IP address or DNS of the server that the client is to synchronisation to. There are a large number of Internet based stratum one and two NTP time servers freely available for public use. Often, educational establishments or government departments maintain these servers, the most well known being the National Institute of Standards and Technology (NIST), which is an agency of the US Department of Commerce. However, there are a number of advantages for organisations in having a local time server. Local dedicated stratum one NTP servers reside much closer to time clients, thus providing much improved accuracy. Additionally, there may be security issues with leaving a port open in the firewall to gain access to Internet based servers. A local server will reside inside the firewall and have no such security concerns. There are a number of external hardware reference clock time sources available to NTP servers. The most accurate and most commonly used being the Global Positioning System. GPS is a US military global positioning system that is widely used for automotive and marine navigation. However, GPS also has a highly accurate timing component. The system can provide precise time to nanosecond resolution, making it ideal as a timing reference. GPS is available subscription-free worldwide. It can be received with a roof-mounted antenna with a good all-round view of the sky. Modern high sensitivity GPS receivers can often operate from an indoor antenna. Additionally, over-determined clock technology allows operation from a single satellite making window located antennas a possibility. National radio time and frequency broadcasts can quite often be received indoors close to a time server. Installation costs can therefore be significantly reduced when compared with GPS based systems. However, weather, local terrain topography and other forms of interference can severely affect radio broadcasts. Radio time references are also not as accurate as time sourced from GPS. A number of national radio broadcasts are available: WWVB in the US, DCF-77 in Germany and MSF in the UK. Generally broadcast ranges of a few thousand miles from the transmitter location are achievable. To summarise, NTP provides a highly accurate and robust method of synchronizing network infrastructure. It can operate with most operating systems to provide a truly universal solution. Many Internet based NTP servers are available to provide a very cost-effective timing reference while GPS and radio reference clocks allow local stratum one servers to be easily installed and configured. Please visit our website for more technical articles and other information about NTP servers at: http://www.ntp-server-systems.com ------------------ ARTICLE END ------------------ [Non-text portions of this message have been removed]
